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-- Semantic analysis.
-- Copyright (C) 2002, 2003, 2004, 2005 Tristan Gingold
--
-- GHDL is free software; you can redistribute it and/or modify it under
-- the terms of the GNU General Public License as published by the Free
-- Software Foundation; either version 2, or (at your option) any later
-- version.
--
-- GHDL is distributed in the hope that it will be useful, but WITHOUT ANY
-- WARRANTY; without even the implied warranty of MERCHANTABILITY or
-- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
-- for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with GHDL; see the file COPYING. If not, write to the Free
-- Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-- 02111-1307, USA.
with Types; use Types;
with Iirs; use Iirs;
package Sem_Expr is
-- Set semantic to EXPR.
-- Replace simple_name with the referenced node,
-- Set type to nodes,
-- Resolve overloading
Deferred_Constant_Allowed : Boolean := False;
-- Semantize an expression (other than a range) with a possible overloading.
-- Sem_expression_ov (and therefore sem_expression) must be called *once*
-- for each expression node with A_TYPE1 not null and at most *once* with
-- A_TYPE1 null.
--
-- When A_TYPE1 is null, sem_expression_ov find all possible types
-- of the expression. If there is only one possible type (ie, overloading
-- is non-existant or solved), then the type of the expression is set,
-- and the node is completly semantized. Sem_expression_ov must not
-- be called for such a node.
-- If there is several possible types (ie overloaded), then the type is
-- set with a list of overload. To finishes the semantisation,
-- sem_expression_ov must be called again with A_TYPE1 set to the
-- expected type.
--
-- If A_TYPE1 is set, sem_expression_ov must finishes the semantisation
-- of the expression, and set its type, which is not necessary a base type.
-- A_TYPE1 must be a base type.
--
-- In case of error, it displays a message and return null.
-- In case of success, it returns the semantized expression, which can
-- be different from EXPR (eg, a character literal is transformed into an
-- enumeration literal).
function Sem_Expression_Ov (Expr: Iir; A_Type1: Iir) return Iir;
-- If A_TYPE is not null, then EXPR must be of type A_TYPE.
-- Return null in case of error.
function Sem_Expression (Expr: Iir; A_Type: Iir) return Iir;
-- Same as Sem_Expression, but also implicitly choose an universal type
-- if overloaded.
function Sem_Expression_Universal (Expr : Iir) return Iir;
-- Same as Sem_Expression but specialized for a case expression.
-- (Handle specific overloading rules).
function Sem_Case_Expression (Expr : Iir) return Iir;
-- Sem COND as a condition.
-- In VHDL08, this follows 9.2.9 Condition operator.
-- In VHDL87 and 93, type of COND must be a boolean.
-- A check is made that COND can be read.
function Sem_Condition (Cond : Iir) return Iir;
-- Same as Sem_Expression but knowing that the type of EXPR must be a
-- composite type. Used for expressions in assignment statement when the
-- target is an aggregate.
function Sem_Composite_Expression (Expr : Iir) return Iir;
-- Return True iif INTER is allowed to be read. Follow rules of
-- LRM08 6.5.2 Interface object declarations.
function Can_Interface_Be_Read (Inter : Iir) return Boolean;
-- Return True iif INTER is allowed to be updated. Follow rules of
-- LRM08 6.5.2 Interface object declarations.
function Can_Interface_Be_Updated (Inter : Iir) return Boolean;
-- Check EXPR can be read.
procedure Check_Read (Expr : Iir);
-- Check EXPR can be updated.
procedure Check_Update (Expr : Iir);
-- Check the type of EXPR can be implicitly converted to TARG_TYPE, ie
-- if TARG_TYPE is a constrained array subtype, number of elements matches.
-- Return FALSE in case of error.
-- If TARG_TYPE or EXPR is NULL_IIR, silently returns TRUE.
function Check_Implicit_Conversion (Targ_Type : Iir; Expr : Iir)
return Boolean;
-- For a procedure call, A_TYPE must be null.
function Sem_Subprogram_Call (Expr: Iir; A_Type: Iir) return Iir;
-- If EXPR is a node for an expression, then return EXPR.
-- Otherwise, emit an error message using LOC as location
-- and return NULL_IIR.
-- If EXPR is NULL_IIR, NULL_IIR is silently returned.
function Check_Is_Expression (Expr : Iir; Loc : Iir) return Iir;
-- Semantize a procedure_call or a concurrent_procedure_call_statement.
-- A procedure call is not an expression but because most of the code
-- for procedure call is common with function call, procedure calls are
-- handled in this package.
procedure Sem_Procedure_Call (Call : Iir_Procedure_Call; Stmt : Iir);
-- Analyze a range (ie a range attribute or a range expression). If
-- ANY_DIR is true, the range can't be a null range (slice vs subtype,
-- used in static evaluation). A_TYPE may be Null_Iir.
-- Return Null_Iir in case of error, or EXPR analyzed (and evaluated if
-- possible).
function Sem_Range_Expression (Expr: Iir; A_Type: Iir; Any_Dir : Boolean)
return Iir;
-- Analyze a discrete range. If ANY_DIR is true, the range can't be a
-- null range (slice vs subtype -- used in static evaluation). A_TYPE may
-- be Null_Iir. Return Null_Iir in case of error.
function Sem_Discrete_Range_Expression
(Expr: Iir; A_Type: Iir; Any_Dir: Boolean) return Iir;
-- Semantize a discrete range and convert to integer if both bounds are
-- universal integer types, according to rules of LRM 3.2.1.1
function Sem_Discrete_Range_Integer (Expr: Iir) return Iir;
-- Transform LIT into a physical_literal.
-- LIT can be either a not semantized physical literal or
-- a simple name that is a physical unit. In the later case, a physical
-- literal is created.
function Sem_Physical_Literal (Lit: Iir) return Iir;
-- CHOICES_LIST is a list of choices (none, expression, range, list or
-- others).
-- If IS_SUB_RANGE is true, then SUB_TYPE may not be fully convered,
-- otherwise, SUB_TYPE must be fully covered.
-- This is used when the subtype of an aggregate must be determined.
-- SUB_TYPE is the discrete subtype.
-- Emit a message if:
-- * the SUB_TYPE is not fully covered by the choices
-- * the choices are not mutually exclusif (an element is present twice)
-- * OTHERS is not the last choice, or is present several times.
--
-- If there is at least one named choice, LOW and HIGH are set with the
-- lowest and highest index.
-- If LOW and HIGH are set, they are locally static.
--
-- Unidimensional strings are not handled here but by
-- sem_string_choices_range.
--
-- TODO:
-- * be smarter if only positional choices (do not create the list).
-- * smarter messages.
procedure Sem_Choices_Range
(Choice_Chain : in out Iir;
Sub_Type : Iir;
Is_Sub_Range : Boolean;
Is_Case_Stmt : Boolean;
Loc : Location_Type;
Low : out Iir;
High : out Iir);
-- Semantize CHOICE_LIST when the choice expression SEL is of a
-- one-dimensional character array type.
procedure Sem_String_Choices_Range (Choice_Chain : Iir; Sel : Iir);
type Compatibility_Level is
(Not_Compatible, Via_Conversion, Fully_Compatible);
-- LEFT are RIGHT must be really a type (not a subtype).
function Are_Basetypes_Compatible (Left: Iir; Right: Iir)
return Compatibility_Level;
-- Return TRUE iif types of LEFT and RIGHT are compatible.
function Are_Nodes_Compatible (Left: Iir; Right: Iir)
return Compatibility_Level;
-- Return TRUE iff the type of EXPR is compatible with A_TYPE
function Is_Expr_Compatible (A_Type : Iir; Expr : Iir)
return Compatibility_Level;
-- LIST1, LIST2 are either a type node or an overload list of types.
-- Return THE type which is compatible with LIST1 are LIST2.
-- Return null_iir if there is no such type or if there are several types.
function Search_Compatible_Type (List1, List2 : Iir) return Iir;
end Sem_Expr;
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